Solution

#include <bits/stdc++.h>
using namespace std;

#define N int(1e6+6)

int arr[N+1];

int main()
{
    #ifdef HOME
     clock_t Start=clock();
     freopen("data1.in", "r", stdin);
     freopen("data1.out", "w", stdout);
    #endif

     int t, ca=1;
     scanf("%d", &t);
     while(t--) {
         for (int i=0; i<=N; i++)
            arr[i]=0;
         int n;
         scanf("%d", &n);
         int a[n];
         for (int i=0; i<n; i++) {
            scanf("%d", &a[i]);
            arr[a[i]]+=1;
         }
         printf("Case %d:\n", ca++);
         for (int i=0; i<=N; i++) {
            if (arr[i]!=0)
                printf("%d %d\n", i, arr[i]);
         }
     }

    #ifdef HOME
     printf("\n>>Runtime: %.10fs\n", (double) (clock() - Start) / CLOCKS_PER_SEC);
    #endif
    return 0;
}